6 



SCIENCE OP GARDENING. 



■uniojured, and they will thus experience a less decided 

 check. Or, if the increase of the plant's subsequent capa- 

 cities for enlarging itself be sought, transplantation, with its 

 necessary destruction of many spongioles, will produce a 

 tendency to throw out a far greater number, and thus give 

 the means of future extraordinary growth. It is pretty 

 generally known that most vegetables possess the power 

 of renewing and indefinitely multiplying their root-fibres, 

 on which the spongelets are situated, wherever these get 

 severed or removed. At the same time, the reduction of 

 the number of spongelets will often, by staying undue 

 luxuriance, induce a state of greater fertility, or entirely 

 bring it about in plants that have previously been barren. 



Newly planted things, being deprived for a time of a 

 large proportion of their spongelets, require a larger 

 supply of liquid food if it be in the growing season, that 

 the spongelets which remain may take up a greater 

 quantity of it, and thus make good the deprivation. It is 

 for this reason that the early autumn is considered pre- 

 ferable for planting all kinds of trees and shrubs, because 

 there is not, for a long period afterwards, any demand upon 

 their resources, and they are able to form new spongelets 

 before these are required. The beginning of the spring, 

 or just before they acquire their full power of vitality, is 

 the next best season, as they then have all the strength of 

 the renewed vital energy to enable them rapidly to form 

 new spongelets. 



The excretions supposed to begivenoff by plants through 

 their spongelets, and which were thought to deteriorate 

 the soil, and render it unfit for a second crop of the same 

 kind, are now proved to have little or no existence. The 

 cause of the deterioration of soils by particular crops, for 

 others of a similar kind, will be found in the fact that 

 certain plants withdraw peculiar gases or elements froul 

 the earth, and these have again to be supplied before 

 similar plants can be satisfactorily grown on the same 

 soil. 



4. — Pores. 



In addition to the spongelets as a means of taking up 

 food, plants are dotted all over the leaves, stems, and even 



